1.5gb wmv to dvd. files too large?

Hello all,
I have googled until I'm blue in the face. I've searched these and other forums...but I surrender. Please help me.

I have a video...
Format: wmv
File size: 1.5Gb
Run time: 6 hours and 47 minutes

Objective:
Burn file to dvd for viewing in dvd player.

Background:
The footage was shot in a classroom of a visiting speaker. Those original files (in .wmv format)were (very highly) compressed by the school staff before I got them. I took those files and assembled them in windows movie maker to create one large file, 1.5Gb.
Now I wish to burn this file to dvd for playback on normal dvd players.

Problem:
Most software won't even open/import .wmv files. But those that did demand massive hard drive space (~25Gb) to process the video. Even using windows movie maker, attempting to save the movie as a DV-AVI requires about 25Gb.

Converting most any format into DVD format results in a larger output file that the original you started with. You in essence answered your own question. That is split the file up into segments that will fit on one or more DVDs.